Trichilia (Meliaceae) Plants: An important source of biomolecules with insecticidal properties

The repeated application of synthetic insecticides has the potential to induce insecticide resistance. Plant extracts are a good source of bioinsecticides, as these extracts often have several bioactive compounds, thus reducing the occurrence of resistance. The genus Trichilia (Meliaceae) is distributed widely in Mexico and it is a sustainable source of bioactive compounds because their bark is shed annually and may be collected without harming the tree. This research evaluated the effect on mortality, weight, larval and pupal duration, fecundity, and fertility of Copitarsia decolora Guenée (Lepidoptera: Noctuidae) when fed with a diet supplemented with different concentrations of hexane, ethyl acetate, acetone, methanol, and aqueous extracts of the Trichilia americana Sessé & Moc., Trichilia hirta L., and Trichilia havanensis Jacq. (Meliaceae) bark. All the extracts provoked a dose-response effect on the variables evaluated. The hexane extract of the 3 species was lethal to the larval stage, with the hexane extract of T. americana being the most toxic of the 3 species, followed by that of T. hirta. The aqueous extract of T. hirta displayed an insecticidal effect on the early instars. The ethyl acetate extracts of T. americana and hexane extracts of T. hirta inhibited growth and induced mortality. The extracts reduced fecundity and fertility of the insect. Extracts of T. americana reduced reproductive potential to a greater extent than did T. hirta and T. havanensis. This research suggests that bark extracts of T. americana, T. hirta, and T. havanensis are a sustainable source of biomolecules.